Manchester United will be without defender Nemanja Vidic for up to ten days following a recurrence of a leg muscle problem.
Vidic missed last weekend's FA Cup defeat to Leeds United after pulling up during the pre-match warm-up and United boss Sir Alex Ferguson has now confirmed the extent of the blow.
The Serbia defender has missed seven Premier League games so far this season and Wes Brown and Jonny Evans will be at the heart of the United defence against Birmingham City on Saturday in the continued absence of Rio Ferdinand.
"During the warm-up against Leeds, he felt a problem in the nerve down the side of his right leg," explained Ferguson.
"It's something which has been a recent problem for him and he just didn't feel confident to play. I understand that because I know it's painful.
"We sent him to a specialist on Wednesday to get the problem diagnosed and we know what exercises we need to do with him now. It's not a long-term problem and we think we can control it."
Vidic could be back for the rescheduled first leg of United's Carling Cup semi-final with Manchester City on January 19.
Meanwhile, Ferguson has given a more positive assessment of fellow centre-half Ferdinand.
The England defender has been out since October with a long-running back problem, but Ferguson believes he could return to first-team action in three weeks.